Panic error during Time Machine backup

I've an issue with my samba installation done with a compiled version of samba 4.9.2 on Ubuntu 16.04 that I would like to use for Time Machine backup.

Time machine backup seems to work, even if it is not very fast, but my problem is that after a while a during the backup I get this panic error:
[2018/12/09 11:43:57.461725, 0] ../source3/locking/share_mode_lock.c:439(share_mode_data_destructor)
  store returned NT_STATUS_UNSUCCESSFUL
[2018/12/09 11:43:57.461915, 0] ../source3/lib/util.c:816(smb_panic_s3)
  PANIC (pid 32610): could not store share mode entry: NT_STATUS_UNSUCCESSFUL
[2018/12/09 11:43:57.463585, 0] ../lib/util/fault.c:261(log_stack_trace)
  BACKTRACE: 45 stack frames:
   #0 /usr/lib/x86_64-linux-gnu/libsamba-util.so.0(log_stack_trace+0x2e) [0x7fa1ab8af95f]
   #1 /usr/lib/x86_64-linux-gnu/libsmbconf.so.0(smb_panic_s3+0x6d) [0x7fa1ab01709a]
   #2 /usr/lib/x86_64-linux-gnu/libsamba-util.so.0(smb_panic+0x28) [0x7fa1ab8af91b]
   #3 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x28a9ad) [0x7fa1ab4fb9ad]
   #4 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3697) [0x7fa1aa9c4697]
   #5 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x492c) [0x7fa1aa9c592c]
   #6 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3852) [0x7fa1aa9c4852]
   #7 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x492c) [0x7fa1aa9c592c]
   #8 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3852) [0x7fa1aa9c4852]
   #9 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(+0x3a13) [0x7fa1aa9c4a13]
   #10 /usr/lib/x86_64-linux-gnu/samba/libtalloc.so.2(_talloc_free+0x105) [0x7fa1aa9c5d79]
   #11 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x1dfefd) [0x7fa1ab450efd]
   #12 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x1e36dc) [0x7fa1ab4546dc]
   #13 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(create_file_default+0x330) [0x7fa1ab45532f]
   #14 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x105027) [0x7fa1ab376027]
   #15 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smb_vfs_call_create_file+0xa9) [0x7fa1ab46131c]
   #16 /usr/lib/x86_64-linux-gnu/samba/vfs/fruit.so(+0x170d3) [0x7fa1932910d3]
   #17 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smb_vfs_call_create_file+0xa9) [0x7fa1ab46131c]
   #18 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x23625a) [0x7fa1ab4a725a]
   #19 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smbd_smb2_request_process_create+0x7ab) [0x7fa1ab4a4d2b]
   #20 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smbd_smb2_request_dispatch+0x13bb) [0x7fa1ab498367]
   #21 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x22b51d) [0x7fa1ab49c51d]
   #22 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(+0x22b637) [0x7fa1ab49c637]
   #23 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_invoke_fd_handler+0x101) [0x7fa1aa5adb66]
   #24 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11422) [0x7fa1aa5b8422]
   #25 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11af6) [0x7fa1aa5b8af6]
   #26 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe30b) [0x7fa1aa5b530b]
   #27 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_once+0x11e) [0x7fa1aa5acd95]
   #28 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_loop_wait+0x25) [0x7fa1aa5ad0e3]
   #29 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe3ad) [0x7fa1aa5b53ad]
   #30 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_wait+0x2b) [0x7fa1aa5ad186]
   #31 /usr/lib/x86_64-linux-gnu/samba/libsmbd-base-samba4.so(smbd_process+0xbdf) [0x7fa1ab47f493]
   #32 /usr/sbin/smbd(+0xdaf9) [0x55e43ec29af9]
   #33 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_invoke_fd_handler+0x101) [0x7fa1aa5adb66]
   #34 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11422) [0x7fa1aa5b8422]
   #35 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0x11af6) [0x7fa1aa5b8af6]
   #36 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe30b) [0x7fa1aa5b530b]
   #37 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_once+0x11e) [0x7fa1aa5acd95]
   #38 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(tevent_common_loop_wait+0x25) [0x7fa1aa5ad0e3]
   #39 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(+0xe3ad) [0x7fa1aa5b53ad]
   #40 /usr/lib/x86_64-linux-gnu/samba/libtevent.so.0(_tevent_loop_wait+0x2b) [0x7fa1aa5ad186]
   #41 /usr/sbin/smbd(+0xe809) [0x55e43ec2a809]
   #42 /usr/sbin/smbd(main+0x190e) [0x55e43ec2caf7]
   #43 /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0) [0x7fa1a7845830]
   #44 /usr/sbin/smbd(_start+0x29) [0x55e43ec22089]

This is my smb.conf configuration

[global]
 load printers = no
 printcap name = /dev/null
 obey pam restrictions = yes
 max log size = 1000
 use mmap = no
 dns proxy = no
 map to guest = bad user
 log file = /var/log/samba/%m.log
 fruit:model = MacPro
 netbios name = sambaudoo
 server role = standalone server
 acl allow execute always = yes
 follow symlinks = yes
 interfaces = wlp3s0
 fruit:advertise_fullsync = true
 server string = Samba Server %v
 wide links = yes
 unix extensions = no
 socket options = SO_KEEPALIVE
 keepalive = 90
 security = user
 fruit:aapl = yes

# Basic Samba configuration

# Special configuration for Apple's Time Machine

## Definde your shares here
[TimeMachine Home]
path = mypath
valid users = %U
writable = yes
durable handles = yes
kernel oplocks = no
kernel share modes = no
posix locking = no
vfs objects = catia fruit streams_xattr
ea support = yes
browseable = yes
read only = No
inherit acls = yes
fruit:time machine = yes
hide dot files = yes

Can someone help me to fix this panic error? Thanks